Moderna shares plunged as much as 25% after partial clinical trial data leaked for its personalized cancer vaccine developed with Merck, despite the full results showing promising outcomes for melanoma patients. Analysts attribute the selloff largely to inflated investor expectations rather than disappointing clinical results. CNBC reports: The personalized vaccine, known as intismeran autogene, paired with Merck's immunotherapy Keytruda reduced the risk of recurrence or death in certain melanoma patients by 42% compared with Keytruda alone. The data also showed the shot along with Keytruda reduced the risk of cancer spreading to distant parts of the body or death by 38%, compared with just the immunotherapy. The companies say about 82% of patients who received the personalized cancer vaccine alongside Keytruda were alive without their melanoma returning at two years, compared with 70% of those who received Keytruda alone. [...] Investors see the targeted vaccine as a possible breakthrough treatment, with the potential to be used in other forms of cancer in the future. It could also offer Moderna a critical additional commercial product in its pipeline, following vaccines for Covid-19, the flu and respiratory syncytial virus. "We assert this relative reduction in recurrence/death is clinically meaningful," said BMO Capital Markets analyst Evan Seigerman. "Such a reaction likely reflects inflated expectations into the full data release, rather than a true indictment on the efficacy of the combo therapy." UBS analysts said "this is overall a strong data set" and gives more confidence in upcoming studies of the vaccine in kidney and bladder cancers. They added the stock reaction may be due more to massive expectations than disappointing data.

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